Altitude compensator



' w. FTISLEY ALTITUDE COMPENSATOR Nov. 4, 1958 Fild Sept. 21, 1955 2 Sheets-Sheet 1 FR-OM ATMOSPHERE INVENTOR. WALTER F. IS'LEY BY w? ATTOR T0 Enema Nov. 4, 1958 v 8 w. F. lSLEY 2,858,821

ALTITUDE COMPENSATOR Filed Sept. 21, 1955 2 Sheets-Sheet 2 FIG.3.

F| 5 I LIINVENTOR.

WALTER F. ISLEY ATTOR EYS United States Patent aALTI'I UDE 'COMPENSATOR Walter 'FLIs'ley, Detroit, Mich assign'or to Continental Motors Corporation, Muskegon, ,Mich., a corporation -of'Virginia vApplication September 21, 11955, Serial-No. 535,693

'12'Claims. (Cl. 123-'140) JM-y invention relates :to a fuel linjection control means for the, purpose :of controlling the: operationof fuel I injec- .ratios, whichare'dependent on changes in engine volumetrics efficiencies under varying operating conditions. Although.many injection pump control devices which are sensitive, to manifold pressures have proven satisfactory in improving engine performance and fuel economy, here- .tofore-a definiteneed existedfor a simple and efficient automatic device which can maintain most desirable fuelair ratios under varying engine operating conditions at changingaltitudes. Basically, .existingfuel injection control means fail to sense the increase in volumetric efficiency with .increasing altitude at constant manifold pressure. The increase in volumetric efficiency of the engines is caused by a reduced exhaust back pressure due to a decrease of atmospheric pressure at altitudes above sea level. Without altitude sensitive control, the fuelrate remains in essentially constant relation to manifold pressures, which decrease with altitude due to lower atmospheric pressures, and the injector therefore is calibrated .to follow a normal meteringcurve, i. e. a reduction in pump fuel output. Hence, .as altitude increases, the lowering fuel rate, in combination with the engines higher volumetric efficiency, results in abnormally low fuel-air ratios or an over lean mixture, thereby preventing optimum :engine performance.

An object of my invention, therefore, is to improve the operating characteristics of fuel-injection engines at varying altitudes by providing an altitude compensating device to modify the manifold pressure control of the fuel injection pump.

Another .object of my invention is to obtain a desired best 'power fuel-air ratio condition at full throttle conditions and a best economy fuel-air ratio condition at part throttle operating conditions regardless of altitude by providing an altitude compensating device which will modify manifold pressure control of the fuel injection pump in differing degree at varying throttle conditions and altitudes.

For a further understanding of my invention, reference may be had to the accompanying drawing which illustrates ,two preferred embodiments of my invention, and ,in which like .characters refer to like ,parts through- .out theseveral views, and in which Fig. l is a vertical'elevational view of aconventional fuel injection pump with pressure control devices installed.

Fig. 2.is .a'cross section elevat-ion'al view'online ,2-2 of :Fig; ,1, illustrating aone :zembodiment :of .amy invention.

:Fig. 3. is asimilar view'fon line 'f2-2 ofFig. 1, illustrating a different "operating position of the mechanism.

Patented Nov. 4, 1958 -.Fig. '4 is another similar view on line 2-2 of Fig. 1'.

Fig. '5 is a-sectionon the line 4-4 ofFig. 2.

Referring to thedrawing in more detail, Fig. 1 shows a conventional engine air induction system having a throttle valve '11 and a supercharger 12. An engine driven variable delivery fuel injection pump 13 of conventional design is shown with its controlling devices mounted thereon, comprising a servo valve 14, an altitudecompensator 15, and a pressure sensitive control 16. A conduit 17 connects-the altitude'compensator with the air induction system 10 on the atmosphere or upstreamside of the throttle 11. Another conduit 18-connects the compensatorlS with-the air induction system 10 on the manifold pressure or downstream side of the throttle 11 and the supercharger 12. The output of the pump 13 is dependent on the-actuation of the servo valve 14 by well knownmeans which arefamiliar to those. skilled in the artand which formno part of the invention herein described.

Fig. 2 shows one type of altitude compensator 15 'designated as adual piston altitude compensator, adjoining and suitably secured or connected to the pressure'se'nsitive control 16 which is shown in part. The pressure sensitive control16 comprises a housing 20 having a pressure control-chamber 21 and supporting a pressure sensitive bellows assembly 22. A pin shaft 23 is connected at one end to the bellows assembly 22 and at the other end to the servo valve 14- (as shownpartially in detail in Fig. 2). Actuation of the pin shaft 23 to theright or outwardly as viewed in Fig. 2 affects the servo valve to decrease the fueloutputx-of the pump, providing lean fuel metering characteristics. Actuation of the pin shaft 23 to the left or inwardly affects the servo valve to increase the fuel outputof the .pumpproviding rich fuel metering characteristics. The position'of the pin 23 is determined by compression and expansion of the bellows assembly 22. This, in turn, is due to the effective changes of air pressureexisting in control chamber 21. In essence, the air pressure in control chamber 21-is the manifold pres sureof the engine, introduced through suitable connections. However,.the manifold pressure is modified and controlled by devices which are fully described and claimed in my copending application Serial No. 370,535, filed July 27, 1953,.now Patent 2,759,469, issued Aug. 21, 19 56 andcopending application Serial No. 370,593, filed July 27., 1953, now Patent 2,749,898, issued June 12, 1956, both of which are entitled Fuel Injection Control.

The altitude compensator 15 is suitably mounted between the pressure sensitive control 16 and the servo valve 14. It comprises apiston housing 24 having a throttle inlet pressure tap 25 open to conduit 17 and a manifold pressure tap 26 open to conduit 18. A central chamber in the piston housing 24 has two portions, namely an altitude pressure chamber 27 and a manifold pressure chamber 28, separatedby a large free-floating power enrichment piston 30, which is slidably mounted on the pin shaft 23. A small auxiliary piston 31 is fixed to the pin shaft 23 and is set within arecess 32 of the large piston 30. A passage 33 in the piston housing 24 connects the throttle inlet pressurextap v25.to the altitude pressure chamber 27. Anotherzpassage34 in the .piston hous ing 24 connects .thernanif'old pressure tap 26 with the manifoldpressure chamber 28. Passages35in the free floating piston open the recess 32::on the inner sideot the small piston '31.-to'ithe.manifold.pressurechamber 28.

The operation of the pressure sensitive con'trol:16,*described in my copending applications aforementioned causes aishiftrof'the :pin s'haft23 'eitherto right sorleft resulting-in 'a' :change :of fuel metering characteristics 1 and hence :fuel-air ratios. The degree of'shift isdeter'mined by theairzpressure in .the control chamber 21', and also by the total effective area of the bellows assembly 22. In effect, the altitude compensator of this invention is so adapted to increase the effective area of the bellows assembly 22 at higher altitudes in order to achieve increased fuel flow. This is accomplished as follows:

At part throttle positions, when manifold pressures are relatively low, the atmospheric pressure in the altitude pressure chamber 27 forces the free floating piston 30 to the right, or away from the small piston 31, as illustrated .in Fig. 3, at which position the free floating piston 36 produces no effect on the control characteristics of the .bellows 22. The small piston 31, however, being fixed to the pin shaft 23, produces a change in the control characteristics of the bellows 22 in direct relationship to the pressure existing in the altitude pressure chamber 27 Due to the connection of this chamber 27 with the engine air induction system upstream of the throttle valve 11 .where atmospheric pressure exists, the pressure in chamber 27 will decrease with any altitude increase due to the corresponding decrease in atmospheric pressure. The manifold pressure existing in chamber 28, passing through passages 35 to that portion of the recess 32 be- .hind or to the right of the piston 31, acts on the piston 31 ;With a force increasing as altitude increases. In other .words, increase in altitude causes an increase in differenltial of pressures introduced at opposite sides of the small .piston 31. Thus, as the altitude increases, a shift to the left of the pin shaft 23 results, causing the servo valve 14 to which it is connected to effect an increase in the fuel output of the pump 13, i. e. to effect a change toward the ,richer fuel metering characteristics. As altitude decreases, the atmospheric pressure in the altitude chamber .27 increases, causing a shift of the pin shaft 23 to the right, then reducing the pump fuel output.

At full power engine operation, the manifold pressure, and hence the pressure in the, manifold pressure chamber :28, increases sufficiently to force the free-floating piston to the left as illustrated in Fig. 2, so that the inner face of the recess 32 bears against the smaller piston 31. -In effect, this motion of the large piston 30 actually increases the effective area of the small piston 31, so that .when altitude increases and the pressure in the altitude chamber decreases, a greater degree of shift to the left or to the rich fuel metering characteristics occurs than can be caused by the small piston 31 alone.

Thus it can be seen that the effective areas of the two pistons can be so constructed'to provide the required ,best power fuel-air ratio at full throttle operating conditions, and best economy fuel-air ratio at part-throttle operating conditions when operating at various altitudes, since the degree of shift will depend on the respective areas of the two pistons.

In Fig. 4, a modification of the embodiment shown in Fig. 2 is shown, and is designated as a single piston altitude compensator, in which everything is identical with Fig. 2 except that a single piston 40 replaces the dual pistons 30 and 31. The operating characteristics of this type of compensator is the same as described for :the

compensator of Fig. 2 for engine full power operation. This altitude compensator is useful in applications for which fuel economy at part throttle is not required. The effective area of piston 40 is essentially the same as the effective area of piston 30 when piston 30 is bearing against piston 31, as explained above.

- While I have illustrated but two embodiments'of my invention, it will be apparent, however, to those skilled in the art to which my invention pertains, that various changes and modifications may be made therein without departing from the spirit of my invention or from the scope of the appended claims.

I claim:

1. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variabledelivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and comprising a pressure sensitive actuator operable only in response to variations in manifold pressure and an altitude compensator operable in response to variations in pressure differenential between manifold pressure and atmospheric pressure to modify the operation of said actuator, and means operatively connecting said actuator with said altitude compensator, whereby to compensate for decreased sensitivity of said actuator due to an increase in altitude, and means selectively actuated in response to an increase in the aforesaid pressure differential beyond a predetermined valve to increase the modifying effect of said altitude compensator on said actuator for high speed engine throttle operation, said last mentioned means being inoperative when the aforesaid manifold pressure is below said predetermined value.

2. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and comprising a plurality of interconnected pressure sensitive instrumentalities operatively connected to. said pump, one of said instrumentalities operable only in response to variations in manifold pressure, and another of said instrumentalities operable in response to variations in pressure differential between manifold pressure and atmospheric pressure, said last mentioned instrumentality comprising an element continuously connected to said first mentioned instrumentality and actuated in response to the aforesaid pressure differential variations during all manifold pres-- sure values to modify the operation of said first mentioned instrumentality and a second element selectively actuated in response'to an increase in manifold pressure beyond a predetermined value to increase the modifying effect of said first mentioned element on said first mentioned instrumentality for high speed engine throttle operation.

3. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and comprising a plurality of interconnected pressure sensitive instrumentalities operatively connected to said pump, one of said instrumentalities operable only in response to variations in manifold pressure, and another of said instrumentalities operable in response to variations in pressure differential between manifold pressure and atmospheric pressure, said last mentioned instrumentality comprising an element continuously connected to said first mentioned instrumentality and actuated in response to the aforesaid pressure differential variations during all manifold pressure values to modify the operation of said first mentioned instrumentality relative to altitude variations, and a second element selectively actuated in response to an increase in manifold pressure beyond a predetermined value to increase the modifying effect of said first mentioned element on said first mentioned instrumentality for high speed engine throttle operation, said last mentioned element being inoperative when the aforesaid manifold pressure is below said predetermined value.

4. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and including an altitude compensator comprising an actuating means operable in response to variations in pressure differential between manifold pressure and atmospheric pressure to modify fuel metering in compensation for changes-in engine volumetric efficiency with changes in altitude, and a second actuating means selectively actuated in response to an increase in manifold pressure beyond a predetermined value to increasev the aforesaid modifying effect of.saidfirst..mentioned actuating means on fuel. metering forihigh. speed engine, throttle operation.

5..,In an internal combustion enginehaving an ,air induction system: including an iair intake manifold, and a .throttlevalve associated, therewith, avariable delivery fuel injection pump, and, a pump-control means operable to vary the fuel metering f .isaid ,pumpijand including an altitude compensator comprising. an actuating means operable in response: to variations. in pressure, difierential between manifold pressure and atmosphericpressure to v,modifyfuel meteringin compensation for changes in enginevolumetric efficiency:withIchangesflin altitude, and

a secondactuating means selectively actuated :only in response to an increase inmanifold pressurebeyond a predetermined value to. increase theaforesaid modifying effect :of said first mentioned actuating means on fuel metering for high speed engine throttleioperation only, \said lastmentioned,.actuatingumeans being inoperative when the aforesaid manifold pressure is :belowsaid .pre-

determined value.

- 6. -In an internal combustion; engine having anairinduction system includingan 'air intake manifold and a throttle valveassociated:therewith, a variable delivery :fuelinjection pump, and a-pumplcontroLmeans operable to vary thefuel meteringof said pump and comprising ashousing structure having. pressurephambers one of said chambers being openly connected only to ?said air 'intakemanifolddownstream. of saidthrottle valve and a pressure sensitive :actuator supported, ,in .said chamber and operable-only in response; to variation of manifold 'pressuret-in said chamber, means operatively-connecting said actuator to said pump-,for-varying; fuel metering of same relative'to-changes Vin manifold pressure, atsecond pressure sensitive actuator movably supported inanother of said chambers and separatingflsame intottwo pressure compartments, oneof-said compartments beingopenly connected-only to said; air intake: manifold 1 downstream of said throttle valve, theothenof saidcompartmentsbeing "openly'connec-ted-only to atmosphere, :means operatively connecting said -;second actuator, to said first actuator,

- 'saidasecond actuator operableinresponse to ,variations of pressuredifferential-between the pressures. in the two compartments to modify :the operation of said firstmentioned actuatorrelative to atmospheric.-pressure changes due -to changes-in altitude, whereby to compensatefor decreased sensitivity-of said actuator due to an increase-in altitude,--said secondactuator comprising avpressure, sensitive element. continuouslyoperatively connected to said firsttactuator and actuated-in responseto the aforesaid pressure differential r variations during all rnanifold pres- "sure .values to modify the operation oft-said first actuator -.'relative=to altitude variations, and a-second pressure sensitive elementselectively actuated in responseto an increase in manifold pressure beyond a predeterminedavalue to.in- 'crease the modifying effect ofsaid first mentioned, element :on said first actuator for high speed-oengineuthrottle operation.

7. In an internal combustion engine having an air induction system including. an air intake manifold and a throttle valve associated therewith,,a variable delivery .fuelinjection pump, and a pump control means operable to vary the fuel metering of said pump and comprising a housingmstructure having pressure chambcrs, one of said chambers beingopenly'connected only-tosaidair intake manifold downstream of said throttle valve and a pressure sensitive actuator supported in said chamber and operable only in response to variation of manifold pressure in said chamber, means operatively connecting said actuator to said pump for varying fuel metering of same relative to changes in manifold pressure, a second pressure sensitive actuator movably supported in another of said chambers and separating same into two pressure compartments, one of said compartments being openly connected only to said air intake manifold downstream of said throttle valve, the other of said compartments .beingv openly. connected only ,toratmosphere, means operatiuelyconnecting saidlsecond actuator to saidfirstactuator,,,s'aid second actuator operable in response to vanations of pressure differential between the pressures 'in ,f-the tworcompartrnents to modify the operation of said first rnentioned, actuator relative to atmospheric pressure fchanges duetochanges in.altitude, whereby to compensateforjdecreasjed sensitivity of said actuator due to an increase in altitude, said second actuator comprising a pressure sensitive element continuously operatively connected to said first actuator and actuated vin response to the aforesaid pressure differential variations during all manifold pressure values to modify the operation of said first actuatorrelative to altitude variations, and a second pressure sensitiveelement selectively actuated in response to an increase in manifold pressure beyond a predetermined value to increase the; modifying effect of said first 'mentioned elementon said first actuator for high speed engine throttle operation, said last mentioned element being 4 inoperative'when' the ,aforesaid manifold pressure is below said predetermined value.

srIn an internal combustion engine having an air "induction-system including an-air intake manifold and athrottle alve associated therewith, a variable delivery fuel injection pump, and a pump control means operable -to vary-the- -f uel metering of said pump and comprising 7 ahousing structure 'having' pressure chambers, one of -saidchambers being' openly, connected only to'said air intake manifold downstream of said throttle valve and apres'sure sensitive actuator supported'insaid chamber and operable onlyin'response to variation of manifold -=pressure"in saidchamber,-means operatively connecting said; actuator to'said pump for varying fuel metering of same-relative tochangesin manifold pressure, a second pressure sensitiveractuatormovably supported in another i of said chambers and separating same into two pressure -cornpartments, one of said .compartmentsgbeing openly connected only-to' said air intake manifold downstream of said'throttle valve, the other of said compartments be- -ing openlyconnected only to atmosphere, means operatively' connecting said' second actuator to said first actumm, said second actuatoroperable in'responseto' variations of pressure differential between the pressures in'the two compartments to modify the operation .of said'first mentioned actuator relative 'to' atrn-ospheric'pressure changes due to changes in altitude, whereby to compensate, for decreased sensitivity of said actuator due to an increase. in .altitude, said second actuatorcomprising a free-floating piston slidably supported in said other chamber and separating said compartments, and free floating piston having a recess in. the side exposed to, the compartment connected to atmosphere, a second piston slidably supported in said recess and closing same from communication with-said compartment connected to atmosphere, a passage in said free-floating piston and openly connecting said recess with the compartment connected to said manifold, saidsecond piston ,rcontiuously. operatively connected to said first actuator and actuated in response to variationsin the pressure differential ibetweengatmos- ,phericpressure. in, said secondcompartrnent and manifold pressure in said recess duringall manifold pressure .values ..,tor.modi fy thesoperation of. said first actuator relativewto ,altitude variations,-v said. free-floating piston; selectively said chambers being openly connected only to said air intake manifold downstream of said throttle valve and a pressure sensitive actuator supported in said chamber and operable only in response to variation of manifold pressure in said chamber, means operatively connecting said actuator to said pump for varying fuel metering of same relative to changes in manifold pressure, a second pressure sensitive actuator movably supported in another of said chambers and separating same into two pressure compartments, one of said compartments being openly connected only to said air intake manifold downstream of said throttle valve, the other of said compartments being openly connected only to atmosphere, means operatively connecting said second actuator to said first actuator, said second actuator operable in response to variations of pressure diiferential between the pressures in the two compartments to modify the operation of said first mentioned actuator relative to atmospheric pressure changes due to changes in altitude, whereby to compensate for decreased sensitivity of said actuator due to an increase in altitude, said second actuator comprising a free-floating piston slidably supported in said other chamber and separating said compartments, and free floating piston having a recess in the side exposed to the compartment connected to atmosphere, a second piston slidably supported in said recess and closing same from communication with said compartment connected to said manifold, said second piston continuously operatively connected to said first actuator and actuated in response to variations in the pressure differential between atmospheric pressure in said second compartment and manifold pressure in said recess during all manifold pressure values to modify the operation of said first actuator relative to altitude variations, said free-floating piston selectively actuated in response to an increase in manifold pressure beyond a predetermined value to coact with said second piston for increasing the modifying effect of same on said first actuator for high engine throttle operation, said free-floating piston being inoperative when the aforesaid manifold pressure is below said predetermined value.

10. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and comprising a housing structure having axially spaced pressure chambers, one of said chambers being openly connected only to said air intake manifold downstream of said throttle valve and a pressure sensitive actuator supported in said chamber and operable only in response to variation of manifold pressure in said chamber, means operatively connecting said actuator to said pump for varying fuel metering of same relative to changes in manifold pressure, a second pressure sensitive actuator axially aligned with the first mentioned actuator movably supported in another of said chambers and separating same into two axially spaced pressure compartments, one of said compartments being openly connected only to said air intake manifold downstream of said throttle valve, the other of said compartments being openly connected only to atmosphere, means operatively axially connecting said second actuator operable in response to variations of pressure differential between the pressures in the two compartments to modify the operation of said first mentioned actuator relative to atmospheric pressure changes due to changes in altitude, whereby to compensate for decreased sensitivity of said actuator due to an increase in altitude, a shaft connecting said first actuator to said pump and slidably extending through said second chamber, said second actuator comprising a free-floating piston axially slidably supported in said other chamber and on said shaft and separating said compartments, said free-floating piston having a recess in the side exposed to the compartment connected to atmosphere, a second piston slidably axially supported in said recess and connected to said shaft, said second piston closing said recess from communication with said compartment connected to atmosphere, a passage in said free-floating piston and openly connecting said recess with the compartment connected to said manifold, said second piston axially actuated in response to variations in the pressure differential between atmospheric pressure in said second compartment and manifold pressure in said recess during all manifold pressure values to modify the operation of said first actuator relative to altitude variations, said free-floating piston selectively axially actuated in response to an increase in manifold pressure beyond a predetermined value to axially coact with said second piston for increasing the modifying effect of same on said first actuator for high speed engine throttle operation.

11. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and including an altitude compensator comprising an actuating means Operable in response to variations in pressure differential between manifold pressure and atmospheric pressure to modify fuel metering in compensation for changes in engine volumetric efficiency with changes in altitude, and a second actuating means constructed and arranged to coact with said first actuating means only when manifold pressure increases beyond a predetermined value and to supplement the modifying effect of said first actuatmg means for high speed engine throttle operation.

12. In an internal combustion engine having an air induction system including an air intake manifold and a throttle valve associated therewith, a variable delivery fuel injection pump, and a pump control means operable to vary the fuel metering of said pump and including an altitude compensator comprising an actuating means operable in response to variations in pressure differential between manifold pressure and atmospheric pressure to modify fuel 'metering in compensation for changes in engine volumetric efficiency with changes in altitude, and a second actuating means constructed and arranged to coact with said' first actuating means only when manifold pressure increases beyond atmospheric pressure and to increase the modifying effect of said first actuating means for high speed engine throttle operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,233,035 Schweizer et al Feb. 25, 1941 2,414,617 Summers Jan. 21, 1947 2,435,902 Reggio Feb. 10, 1948 

